Vacuum rollers and air turn bars (hereinafter “air turns”) are used in web handling applications to create differential tension on either side of the roller (tension isolation), to only allow contact on one side of the web (as opposed to pinch rollers which contact both sides), and to reverse the direction of the web flow, respectively. State-of-the-art vacuum rollers and air turns may possess certain features and characteristics which drive up cost and negatively affect quality.
In the case of common vacuum rollers, tension isolation is accomplished using an inner stationary member which comprises the desired wrap angle. Vacuum is generated within an inner stationary member via a vacuum pump, and when a rotating outer roller passes over the wrap angle portion, vacuum is conducted through a series of holes in the surface of the outer roller, and thus generates the desired friction over the wrap angle. For current art designs, the inner member and the outer roller must have very precise mating surfaces so that vacuum pressure does not escape. Three of the biggest issues with the current technology is that: (1) it is very expensive due to the elaborate design and precision components required, (2) the vacuum flow rate is high, and the vacuum pressure is low, and (3) the web may be marked by the holes in the outer rotating roller.
Common turn rollers are used in web handling to change the direction of the web as it progresses through its course. State-of-the-art air turns employ the use of pressurized air to lift a web off of the surface of the roll. These are typically manufactured from metal components by creating an arc through which air is passed through a series of channels, utilizing a variety of configurations, such as provided by Advance Systems, Inc. (ASI). These systems, due to the amount of escaping air, typically have high flow rates. Also, as in the case of vacuum rollers, the web may be marked by the air passageways over which the web passes, in the event of contact.